The project proposes to introduce a laboratory-tested "videogame" simulation of cognitive performace to the highest risk group for drinking and driving arrests and crashes: the yound adult, age 18-24. The first phase of the project refines the software and hardware of a laboratory prototype divided-attention task (SEDI). The final product of Phase I will be a simulation of SEDI that can be adapted to a commonly available microcomputer system (Apple II). Phase I also evaluates the new simulation with a sample of young adults by replicating previous laboratory research conducted with the prototype. The proposed study will establish the slope and intercept of the BAC-impairment function with a repeated measures design that exposes subjects to placebo and two alcohol doses across sessions. New and previously collected data sets will then be used to write "BAC handicaps" into the SEDI software so that future participants can experience impairment effects without consuming alcohol. Phase II evaluates the reliability of the handicaps and the effectiveness of the simulation as a drinking and driving countermeasure in the high school driver education curriculum. The microcomputer SEDI should have commercial appeal because it will be a low cost, portable and entertaining driving simulation that requires active participation from the student.